Grain-filling characteristics and yield differences of maize cultivars with contrasting nitrogen efficiencies^☆

To investigate the effect of nitrogen management on the grain-filling characteristics and yield formation of maize cultivars with contrasting nitrogen efficiencies, and to identify differences in grain-filling characteristics and yield of maize cultivars in response to nitrogen management, a two-year field experiment was conducted in southwest China in 2015–2016. The grain-filling rate and duration of the N-inefficient cultivar XY 508 were higher than those of the N-efficient cultivar ZH 311. The 100-kernel weight of XY 508 was significantly higher than that of ZH 311. The kernel number per ear of ZH 311 was significantly higher than that of XY 508, making the population filling rate of ZH 311 significantly higher than that of XY 508. The higher population filling rate of the N-efficient maize cultivar led to a significant yield advantage over the N-inefficient maize cultivar. Nitrogen management effectively improved maize grain yield, but the response of maize cultivars with contrasting nitrogen efficiencies to nitrogen management was inconsistent. A basal fertilizer ratio 60.43% with a topdressing ratio 39.57% effectively increased grain-filling rate, delayed the time to maximum filling rate, prolonged the active filling period and effective grain-filling time, increased the 100-kernel weight, and maintained higher kernels per ear, thereby improving the population filling rate and maximizing the yield advantage of the N-efficient cultivar. A 100% basal fertilizer ratio not only increased the number of kernels per ear, but also maintained high grain filling characteristics to obtain a higher 100-kernel weight and increased the population filling rate, leading to a high grain yield in the N-inefficient cultivar. Thus, the 100% basal fertilizer ratio partially compensated for the deficient grain yield of the N-inefficient cultivar.